Hello,

This KMZ file displays time-based track sections of the London Underground that use the new <TimeSpan> functionality of KML 2.1 and the latest Beta 4 version of GE.

If you have this latest version installed, clicking the 'play' button on the new slider bar at the top of the screen will play an animation of the development of the London Underground system from the first section of track opened in 1863 to the current network in 2006.

The view defaults to the Greater London area. However, you can zoom out to include the westerly destinations that the Metropolitan and District lines reached or zoom in to the central area where the contentration of track is greater.

I would recommend setting the speed of the animation to slow (click on the clock icon next to the slider to find the menu).

This is not meant to be a terribly accurate and comprehensive history of Tube network - timespans and track sections are approximate - but it gives a nice impression of the growth of the system.

Have a look at this post for more about the new time-based functionality of the latest GE release:
http://bbs.keyhole.com/ubb/showthreaded.php/Cat/0/Number/596077



Cheers,

Simon.